Returns remaining API call limit, divided by the time remaining before the next reset, as a ratio of the total rate limit per hour.

For example, if rate_limit is 150, the total rate is 150 API calls per hour. If rate_remaining is 75, and there 1800 seconds (1/2 hour) remaining before the next reset, rate_ratio returns 1.0, because there are exactly enough API calls remaining to maintain he full rate of 150 calls per hour.

If rate_remaining is 30 and there are 360 seconds remaining before reset, rate_ratio returns 2.0, because there are enough API calls remaining to maintain twice the full rate of 150 calls per hour.

As a final example, if rate_remaining is 15, and there are 7200 seconds remaining before reset, rate_ratio returns 0.5, because there are only enough API calls remaining to maintain half the full rate of 150 calls per hour.

Returns the number of seconds to wait before making another rate limited API call such that $target_ratio of the full rate would be available. It always returns a number greater than, or equal to zero.

Use a target rate of 1.0 in a timeline polling loop to get a steady polling rate, using all the allocated calls, and adjusted for other API calls as they occur.

Use a target rate < 1.0 to allow a process to make calls as fast as possible but not consume all of the calls available, too soon. For example, if you have a process building a large social graph, you may want to allow it make as many calls as possible, with no wait, until 20% of the available rate remains. Use a value of 0.2 for that purpose.

A target rate > than 1.0 can be used for a process that should only use "extra" available API calls. This is useful for an application that requires most of it's rate limit for normal operation.